1. Field of the Invention
This invention generally relates to a method of inducing strain in bone tissue, and more specifically relates to a method for preventing osteopenia, and promoting growth, ingrowth and healing of bone tissue by mechanically loading the bone tissue.
2. Description of the Prior Art
Numerous publications and patents disclose various methods of maintaining or promoting bone tissue growth. For example, Ryaby, et al. U.S. Pat. Nos. 4,105,017, 4,266,532, 4,266,533 and 4,315,503 collectively describe means and methods for inducing voltage and current signals in bone tissue for the treatment or repair of bone fractures. Kraus, et al. U.S. Pat. No. 3,890,953 discloses stimulating the healing of fractures by the application of magnetic fields, the effect of which is described as introducing mechanical stress.
U.S. Pat. No. 4,530,360 which issued to Luiz Duarte discloses a method for healing bone fractures by the application of ultrasound. Also, the piezoelectric response of mechanically stressed bone is disclosed in the article, Generation of Electric Potentials by Bone in Response to Mechanical Stress, published in Science Magazine 137, 1063-1064, Sept. 28, 1962.
Many conventional methods of promoting bone tissue growth and bone maintenance by the application of mechanical loads generally tend to apply relatively low frequency or low repetition rate, relatively high magnitude loading. Such loading not only may not be necessary but also may be detrimental to bone maintenance and well being.
The maintenance of bone mass is commonly believed to be regulated by the peak loads experienced by the bone. Thus, prescribed techniques for mineralization include aggressive exercise or even impact loading, for example, heel drops. For the elderly, these treatment protocols can be difficult to maintain or even dangerous. High loading activity could precipitate the fracture that the exercise was supposed to prevent.